Whisk together buttermilk, mustard, garlic and hot sauce in a shallow glass dish. Add chicken and turn to coat. Cover and marinate in the refrigerator for at least 30 minutes or for up to 8 hours.

Preheat oven to 425°F. Grease a cookie sheet or baking pan. Whisk flour, sesame seeds, paprika, thyme, salt and pepper in a small bowl. Place the flour mixture in a paper bag. Shaking off excess marinade, place one or two pieces of chicken at a time in the bag and shake to coat. Place the chicken on the prepared pan. Spray the chicken with cooking spray. Bake until golden and no longer pink in the center, 40 to 50 minutes. Serves 4.